Amphibian Reproduction - Anatomy & Physiology

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Introduction

Reproductive behaviour and physiology shows much placicity in amphibians. Gender and breeding season are controlled by genetics, photoperiod, temperature, humidity and food or mate availability.

Reproductive Traits

Amphibian reproduction can by classified by primitive traits that are shared by most fish (Oviparity, Anamniotic Eggs and a Cloaca). They also show derived traits (Metamorphosis, Ovoviviparity and Population Sex Modulation).

Oviparous

• Lay eggs with little or no embryonic development within the mother.
• Eggs laid singly,in clusters or in strands depending on the species of amphibian.

Ovovivparous

• Evident in a few species of frog and salamander.
• Ovoviviparous animals develop within eggs that remain within the mother's body up until they hatch or are about to hatch. * * It is similar to vivipary in that the embryo develops within the mother's body.
• Unlike the embryos of viviparous species, ovoviviparous embryos are nourished by the egg yolk rather than by the mother's body.
  • However, the mother's body does provide gas exchange.

Anamniotic Eggs

• No shell.
• Require moisture as there is only a single membrane around the embryo.
  • Amnion is absent.

Cloaca

• Shared urinary, reproductive and excretory channel.

Species Differences

Caecilians (Gymnophiona)

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